Maintenance and protection devices for cooling plants

ABSTRACT

In a single circuit refrigeration plant, a refrigerant gas stream while flowing in the circuit is compressed by a compressor, circulated from the pressure side of the compressor through a condenser, then an evaporator and finally back to the suction side of the compressor. A housing is provided having two concentrically located contiguous compartments. Of these, the first compartment is interposed between the pressure side of the compressor and the condenser. The second compartment is interposed between the first compartment and the refrigerant gas return line to the suction side of the compressor. In the first compartment, the compressed refrigerant is degassed and forwarded to the condenser and the separated oil, still having some gas dissolved in it is forwarded under pressure to the second compartment. There, the pressure is released, the oil is degassed and returned to the compressor and the separated gas is combined with the refrigerant return line from the evaporator to the suction side of the compressor. While the degassed separated oil is in the second compartment, it is cooled by indirect heat exchange with the atmosphere surrounding the second compartment.

REFERENCE TO RELATED APPLICATION

This is a division of my copending U.S. patent application Ser. No.171,186, filed July 22, 1980 now U.S. Pat. No. 4,329,854 issued May 18,1982.

FIELD OF THE INVENTION

The invention relates to a supply and protective device forrefrigeration plants, especially for compressor refrigeration plants.

BACKGROUND OF THE INVENTION

Separate oil-separators, oil degassification-/oil collecting vessels,fluid traps as well as fluid collectors have been known in refrigerationplants.

The invention is based on the task of developing a device of theinitially stated type in such a way that it may be applied universally,needs little space and ensures an economical and energy favorableoperation of the refrigeration plant and takes care essentially of asystematic and sure operational return of oil and protects just aseffectively against fluid impact.

SUMMARY OF THE INVENTION

According to the invention, devices with at least two operative spaces,disposed mutually concentrically, are provided, whereby differentfunctions may be assigned to these operative spaces. Preferredembodiments of the invention are devices with three and four operativespaces.

In case of a device with at least two operative spaces the operationalprocesses of "separating oil from the compressed gas stream" and "oildegassification of the return oil", or instead of the latter "separatingof fluid from the producer gas stream: may take their course, or theoperational processes may also be provided in different combination incase of devices with three and four operational spaces, whereby thefunction of "collecting fluid of the condensor freezing mixture fluid"is added.

The operational spaces separate the circulation media, however theoperational spaces are so disposed relative to one another, that afavorable mutual influencing results. The device fulfills universal,overwhelmingly separating functions. The disposal of the operationalspaces is determined according to economics, constructions, functionaland thermodynamic points of view, whereby the constructional design withoperation spaces disposed concentrically side by side and on top of oneanother, represents an optimum. In this case supply and protectiveeffects are partly interconnected.

In the following pages the listed abbreviations will be used for theindividual functions:

Separating oil from the compressed gas stream=OeS

Oil degassification of this return oil=E

Fluid separation from the production gas stream=FA

Fluid collection of the condensor-freezing mixture fluid=FS

The multiple supply effects of the device with four operational spacesare:

1. Effective, nearly complete separation of the refrigeration engine oilfrom the compressed gas volume stream of the compressed gas line in theOeS operation space by corresponding construction elements (filter body,baffle plate) and volume-size according to function, as well as oilreturn according to operation (floating ball-mechanism) in theE-operation space, whereby type and position of the feed is codeterminedby the degassing task (gas space, distance to the oil level and to thedegassing line, which are also characteristics of the invention).

2. Effective degassing of the return oil in the E-operating space bypressure release via a degassing arrangement (for example: degassingvalve with successive steam dome and pressure section for continuousdegassing effect, also characteristics of this invention) as well assufficient oil supply. Cooling of the fed-in return oil in the feed line(as smooth pipe, ribbed pipe or coil) in the area of the FA operatingspace, but also by its cooling effect on the stored oil in theE-operation space, assuming corresponding constructional coordination asadditional inventive characteristics. Pressure-constant return of thedegassed and cooled-down oil to the crank pit of the refrigerationcompressor via an oil-level regulator (floating ball mechanism) providedthereon.

This entire self contained course of the oil separation, float-regulatedoil return, degassing and cooling-down under thermally favorableinfluences, in brief, favorable transitions of flow within thisapparatus is likewise a characteristic of the invention.

It represents an optimum both from a constructional, but also from afunctional point of view, for in this device the oil is separated at ahigh degree of effectiveness (saving energy, since only theinsignificant residual oil takes energy from the refrigerating mediumand is transported through the refrigerating circuit and influences thedegree of effectiveness of the refrigerating plant negatively, also anyshifting of oil and damage is returned in a quantity mechanicallycontrolled (safely), is then degassed immediately (oil frothing in therefrigerating compressor and any damage resulting from it will thereforebe avoided) and is cooled down at the same time (therefore unnecessaryheating up of the compressor bearings is thus averted).

This apparatus thus represents a desirable supply arrangement withseveral protective effects for the refrigerating compressor,particularly because a complete oil supply is achieved.

Refrigeration engine oil returned from the stream of compressed gas,usually contains dissolved refrigerating agent. During start and inoperation of the refrigerating compressors damage to the compressoroften results from this (fluid impact, valve-tongues, even breakage ofvalve plates, damage in storage, etc.).

Therefore, crank-pit heaters (electric) or pumping down circuits arecustomarily provided as a precaution, in order to drive out or suck-outthe refrigerant dissolved in the oil. This costs additional power andpartly a greater use of devices.

The hot refrigerating engine oil (t_(OeS) >t_(E)) separated in the OeSoperating space for example by way of filters and baffle plates isconducted for example by way of a mechanical float valve to theE-operation space. As a result of the effect in the E-space and the heatflow from the OeS space, corresponding constructional space coordinationand assuming the shaping of the heat exchange surface, and correspondingconstructional space correlation and forming of the heat exchangesurface the following thermo-dynamic effect connected with the inventionwill be achieved:

Degassing by pressure release (pE<p0eS), essentially supported bythermal driving-out of gas (g0eS→gE).

As a result of thermal influence of the FA-space (t_(FA) <t_(E)), butalso by corresponding passing through pipes through the FA space, orelse by guiding into an additional space connected with the ambient air(t_(R) <t_(E)), an important, thermodynamic reciprocal effect will beachieved moreover, since the return oil is advantageously cooled down,and the liquid separated in the FA-operation space and the productiongas, flowing through the former is heated up advantageously.

For this purpose corresponding constructional disposal of the operatingspaces, the components, the use of for example, heat conductive but alsothermally insulating surface areas, also for example variable assignmentof the spaces, of the components and the connections are postulated (incase of the FA-space, for example, the heating of the producer gas iscontrolled by variable position of the connections, which is also aspecial characteristic of this invention).

Multiple protective effects of the device with four operating spaces:

1. Effective, reliable separation of the fluid moved to the producer-gasside or carried long by the producer-gas volume (freezing mixture,residual oil or their mixtures) and moreover their continuous, mist-liketherefore properly protective return (by way of Venturi tube withpipette) from the FA operating space with systematic volume to therefrigerating compressor through its producer-gas volume-stream. As aresult of that the following injuries to the compressor will beeffectively avoided on the basis of this system:

Shrinking-on of the bearings (undercooling),

Fluid impacts (hammering of the pistons, breaking of the operatingvalves, pistons, eccentric or crank shafts, tearing of gaskets),

Impeding the lubricating oil supply (formation of oil foam, damage tobearings).

The systematic volume, as a function of the refrigeration performanceand of the plant size, will be achieved for fairly large receivedquantities of separated fluid by parallel connection of acorrespondingly large container via communicating pipe toward the FAoperating space.

2. Effective undercooling (tu<t) of the freezing mixture fluid in the FSoperating space emerging from the condenser via the fluid line,especially as a result of the cooling effect of the FA operating space,assuming the effective correlation of both operating spaces.

The undercooling has the following advantages and protective effects forthe plant operation:

(a) No pre-evaporation (possible consequences: cavitation, hammering ofthe expansion valve) in case of standard loss of pressure in the fluidline.

(b) No pre-evaporation in case of an extended fluid line.

(c) Increase of the refrigerating capacity (greaterenthalpy-difference).

Beside these protective effects and the improvement of the performanceof the refrigerating plant, the positive thermo-dynamic interaction ofboth operating spaces should be noted. As a result of the heat flow fromthe FS operating space to the FA operating space, assuming correspondingstructural correlation, not only the fluid in the FS operating space iscooled down, but the producer gas volume stream and the separated fluid(freezing mixture, residual oil and their mixtures), guided through theFA operating space are heated up advantageously (tFL, toh>to).

Advantages: Low viscosity of the oil-freezing agent mixture sucked-infrom the FA operating space even in case of low temperature operation,also not too low a producer gas input temperature in the refrigeratingcompressor, the heating up the producer gas volume stream in the FAoperating space may be influenced by the distance and the position ofthe inlet and outlet, which is also a characteristic of this invention.The systematic volume as a function of the refrigerating performance andsize of plant is achieved for fairly large fluid receptions by parallelconnection of a correspondingly large container via communicating pipestowards the FS operating space.

The described multiple effects have hitherto not become known as a workcycle in a closed construction unit, with the complex, favorablethermodynamic reciprocal effects, resulting therefrom.

Additional thermodynamic effects, functions and extremely favorableoperating processes characterize this invention not only as a newtechnique, but also as a desirable, complete supply and protectivearrangement for the reliable oil supply of refrigeration compressors forthe ensured protection against fluid impacts on the suction side(UVV-requirement-accident prevention rule) and beyond that because ofadditional supply and protective tasks, already described, as a centraland universal device with many advantages of construction and plant.

The devices may be developed in a corresponding manner with two andthree operating spaces, whereby always two or three of the functionsdescribed before are assigned to the operating spaces. Here, variouscombinations of functions are possible.

The devices are therefore suited for universal use in supply andprotection in refrigerating plants and for a just as effectiveprotection against fluid impacts, especially for compressorrefrigerating plants, single circuit or combination refrigeratingplants, in single, double or multiple step construction or in cascadeconnection.

The building and connection structure of the devices resulting from theinvention, permits moreover a simple connection or a simpleaccommodation of control and/or single arrangements in the correspondingoperating spaces in order to record fluid levels or to regulate them.The new technique of this invention, its functional and operationaladvantages appear in an unexpected way in case of its use in combinationrefrigerating plants.

Embodiments of the invention will be described in more detailsubsequently, on the basis of the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow diagram of a single circuit refrigeration plant with asingle stage compressor and four concentrically arranged operatingspaces;

FIG. 2 is a flow diagram of a single circuit refrigeration plant with atwo-stage compressor, a fluid undercooler and four concentricallyarranged operating spaces;

FIG. 3 is a schematic representation of the apparatus that is diagrammedin FIG. 1;

FIG. 4 is a flow diagram of a single circuit refrigeration plant with aone-stage compressor and three concentrically arranged operating spaces;

FIG. 5 is a schematic representation of the apparatus that is diagrammedin FIG. 4;

FIG. 6 is a schematic representation of a modified form of the apparatusof FIG. 5;

FIG. 7 is a flow diagram of a single circuit refrigeration plant with aone-stage compressor and two concentrically arranged operating spaces;and

FIG. 8 is a schematic representation of the apparatus that is diagrammedin FIG. 7.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

In the figures the numeral 1 designates an operating space for oilseparation from the stream of compressed gas, 2 is an operating spacefor oil degassing of this return oil, 3 for separating fluid from theproducer gas stream and 4 is an operating space for collecting fluid ofthe condensor freezing agent fluid, whereby the individual operatingspaces may also assume some other mutual arrangement.

FIG. 1 shows the flow diagram of a single circuit refrigerating plantwith single stage compressor (7) and device UA4 (four functions). Forthe operating spaces OeS (1), E (2), FA (3) and FS (4) the followingworking interrelation result therein:

The stream of freezing mixtures of the refrigerating circuit produced bythe refrigerating compressor (7), enters at first as a compressed gasvolume stream (V) via the pressure gas line (12) into the OeS operatingspace (1).

There the compressor oil carried along by the pressure gas-volume streamis almost entirely separated and is conveyed into the E-operating space(2) under pressure gas pressure (p) in the rhythm of operationallyobtained quantities.

Here, the pressure gas dissolved in oil is relaxed at a lower pressure((po+Δp)<p) and is carried off to the FA operating space (3) via adegassing valve (6). The oil degassed and stored in the D-operatingspace (2) is cooled off by the cooling action of the FA operating space(3) (tFA<tE).

The pressure gas volume stream (V) reaches the condensor (8) from theOeS operating space (1) via a series connected return valve (15) in thepressure gas line (12). The freezing mixture fluid emerging there movesvia the fluid line (13) into the FS operating space (4), where it isundercooled by the cooling action of the FA operating space (4), whereit is undercooled by the cooling action of the FA operating space (3)and of the ambient air.

The undercooled freezing mixture fluid flows from the FS operating space(4) through the fluid line (13) to the cut-off valve (10), where itrelaxes to evaporation pressure (po) and is injected into the evaporator(9).

The evaporated freezing mixture enters the FA-operating space (3) as aproducer-gas volume stream (Vo) via the producer gas line (11). Here theliquids, carried along the producer gas volume stream or which movedaway from the direction of the fluid side (freezing mixture, residualoil or their mixtures) are effectively separated and collected. Thesefluids are continuously sucked off in a protective form by therefrigerating compressor (7) via the producer gas line (11) with theemerging producer gas volume stream.

The degassed and cooled down return oil, stored in the E-operating space(2), reaches the crank pit of the refrigerating compressor (7) underconstant differential pressure (Δp) through an outlet-shut-off valve (5)and an oil return line (17) by way of an oil-level regulator (14).

FIG. 2 shows the flow diagram of a single circuit refrigerating plantwith a two-stage compressor (18), fluid undercooler (25) and device UA4.An active correlation analogous to the one described under FIG. 1 forthe operating spaces OeS (1), E (2), FA (3) and FS (4), whereby thefollowing effects connected with the two-stage operating must be takeninto consideration: The pressure gas volume stream (V) enters the highpressure stage (2) into the refrigerating circuit, the producer-gasvolume stream (Vo) is produced by the low pressure stage (19) of thetwo-stage refrigerating compressor (18). In this case almost meanpressure (pm) prevails in the crank pit, since there is a connection tothe mean pressure area (21). This causes a pressure ((pm +Δp)<p) greaterthan the mean pressure (pm) in the E-operating space (2). By degassingtoward the mean pressure area (21) this will be achieved. The degassingline (24) is connected for this purpose with the fluid injection line(23) between cut-off valve (22) for the intermediate injection and fluidundercooler (25).

FIG. 3 shows the embodiment of a constructed device UA4 with anoperating spaces system (OeS (1), E (2), FA (3), FS (4)) and activecorrelations as described under FIG. 1.

FIG. 4 shows the flow diagram of a single circuit refrigerating plantwith one stage compressor (7) and device UA3 for the three operatingspaces of which the functions contents OeS (1), E (2) and FA (3) aremade the basis. Thus the following effective correlations result:

The stream of freezing mixture of the refrigerating circuit, produced bythe refrigerating compressor (7) enters at first as pressure gas volumestream (V) by way of the pressure gas line (12) into the OeS-operatingspace (1). The compressor oil, carried along by the pressure gas volumestream is almost completely separated and is conveyed into theE-operating space (2) under pressure gas pressure (p) in a quantityobtained in the rhythm of the operation. Here, the pressure gasdissolved in the oil is relaxed at low pressure ((po+Δp)<p) and iscarried off to the FA-operating space (3) via a degassification valve(6). The oil degassed and stored, in the E-operating space (2) is cooleddown by the cooling action of the FA operating space (3) (tFA<tE).

The pressure gas volume stream (V) reaches the condensor (8) from theOeS operating space (1) via a series connected non-return valve (15) inthe pressure gas line (12). The freezing mixture fluid emerging there isabsorbed by the following plant fluid collector (32) and is undercooledby the ambient air. The undercooled freezing mixture fluid continues toflow to the cut-off valve (10), where it is relaxed to evaporationpressure (po) and is injected into the evaporator (9).

The evaporated freezing mixture enters the FA operating space (3) viathe producer gas line (11) as a producers gas volume stream (Vo). Herethe fluids (freezing mixture, residual oil or their mixtures) carriedalong by the producer gas volume stream or moved away from the directionof the fluid side, are separated effectively and collected. These fluidswith the emerging producer gas volume stream are continuously sucked offin a protective form by the refrigerating compressor (7) via theproducer gas line (11).

The degassed and cooled down return oil stored in the E-operating space(2) reaches the crank pit of the refrigerating compressor (7) underconstant differential pressure (Δp) through an outlet and cut-off valve(5) and oil return line (17) via an oil level regulator (14).

FIG. 5 shows the embodiment of a constructed device UA3 withoperating-spaces system (OeS (1), E (2), FA (3)) and effectivecorrelations, as described under FIG. 4.

FIG. 6 shows another embodiment of the device UA3.

FIG. 7 shows the flow diagram for a single circuit refrigerating plantwith one-stage compressor (7) and device UA2, the function contents OeS(1) and E (2) have been made the base for its two operating spaces. Thusthe following effective correlations result:

The stream of freezing mixture of the refrigerating circuit, produced bythe refrigerating compressor (7) enters the OeS operating space (1)first as a pressure gas volume stream (V) via the pressure gas line(12). There the compressor oil, carried along by the pressure gas volumestream is almost completely separated and is conveyed under pressure gaspressure (p) into the E-operating space (2) in the rhythm ofoperationally obtained quantity. Here the pressure gas dissolved in theoil is relaxed at low pressure ((po+Δp)<p) and is carried off via adegassing valve (6) and degassing line (24) to the producer gas line(11). The oil, degassed and stored in the E-operating space (2) iscooled down by the cooling effect of the ambient air (t air<tE).

The pressure gas-volume stream (V) reaches the condensor (8) from theOeS-operating space (1) via a series connected return valve (15) in thepressure gas line (12).

The evaporated freezing mixture enters the refrigerating compressor (7)from the evaporator (9) as a producer gas volume stream (Vo) via theproducer gas line (11) and plant fluid separator (16).

The degassed and cooled down return oil, stored in the E-operating space(2) reaches the crank pit of the frigerating compressor (7) underconstant differential pressure (Δp) through an outlet and cut-off valve(5) and oil return line (17) via an oil level regulator (14).

FIG. 8 shows an embodiment of a device UA2 according to FIG. 7.

The operating space 3 with the Venturi nozzle schematically rendered inFIGS. 3, 5 and 6, is preferably developed corresponding to the fluidseparator with exhaust nozzle, described in the German OS 2 602 582.

Beside the various arrangements and places of the operating spaces shownin the Figures, the following operating space positions may be provided,whereby places and arrangements are moreover permutative in all theindividual cases: Side-by-side, superposed, concentrically superposed,concentrically side-by-side and superposed.

Beside these different positions of the operating spaces a basicallystar-shaped arrangement may be provided, whereby the operating spacesmay be disposed in the form of a rectangle or a square or as sectors ofa circular cross-section, so that one operating always adjoins twoadjacent operating spaces.

What is claimed is:
 1. In a single circuit refrigeration plant in whicha gas stream, while flowing in the circuit, is compressed by acompressor which injects oil into the gas stream while compressing thegas stream, circulated from the pressure side of the compressor andthrough a condensor, then through an evaporator and finally back to thesuction side of the compressor,an apparatus improvement, comprising: ahousing having wall means defining two concentrically located contiguouscompartments, each being interposed in said single circuit at arespectively different relative location as follows: (a) a firstcompartment being interposed between the pressure side of the compressorand the condenser; (b) a second compartment being interposed between thefirst compartment and the suction side of the compressor; there beingfurther provided in said circuit a degassing valve between the secondcompartment and the suction side of the compressor, a non-return valvebetween the first compartment and the condenser, and a fluid collectorbetween the condenser and the suction side of the compressor; therebeing further provided a gas pressure-operated means connecting saidfirst compartment with said second compartment for deliveringpressurized oil separating from said compressed gas stream in said firstcompartment to said second compartment with some gas dissolved therein;and conduit means for delivering degassified oil collecting in thesecond compartment back to the compressor; the first compartment beingaxially centrally located and directly ringed by the second compartment,so that, in operation: as the compressed gas stream enters the firstcompartment the pressurized oil therein separates therefrom and theresultingly de-oiled compressed gas stream flows to and through thecondenser, to and through the evaporator, is combined with the gas thatis degassed from the oil in the second compartment, and the resultinggas stream is returned to the suction side of the compressor, meanwhile,the oil degassed and collected in the second compartment is cooled atleast in part by indirect heat transfer with the atmosphere exteriorlyof the apparatus and is returned to the compressor, so that the twocompartments serve the following principal functions: oil is separatedfrom compressed gas in the first compartment and separated oil isdegassed in the second compartment.
 2. In a single circuit refrigerationplant which includes:a compressor having a suction side and a pressureside, a condenser, and an evaporator with conduit means operativelyconnecting these elements in a single circuit, the improvement forrecovery of compressor oil which becomes entrained in the refrigerantgas as the refrigerant gas is compressed and issues into the conduitmeans at the pressure side of the compressor, said improvementcomprising: a housing having wall means defining two concentricallylocated, contiguous compartments including a first, centrally-locatedcompartment and a second, annular compartment which rings the firstcompartment; the first compartment being interposed in said conduitmeans of said single circuit between the pressure side of the compressorand the condenser; the second compartment being interposed in saidconduit means of said single circuit between the first compartment and asite on said conduit means where the refrigerant gas is returning fromthe evaporator to the suction side of the compressor; the firstcompartment being constructed and arranged to degas the compressedrefrigerant, forward the deoiled compressed refrigerant along saidconduit means to the condenser, and forward the separated oil under gaspressure to the second compartment with some refrigerant as stilldissolved in the separated oil entering the second compartment; thesecond compartment being constructed and arranged to degas the separatedoil, permit indirect heat transfer from the degassed separated oil tothe ambient air, return the thus-cooled degassed, separated oil to thecompressor, and to combine the refrigerant gas separated from the oil inthe second compartment with the refrigerant gas that is returning fromthe evaporator to the suction side of the compressor.